Process for the separation of complex ores.



WILLIAM MORLEY MIARTIN OF REDRUTH, ENGLAND.

PROCESS FOR THE SEPARATION OF COMPLEX ORES.

No Drawing. Application filed February 23,

Specification of Letters Patent.

Patented J uly 8, .1913.

1910. Serial No. 545,520.

lie it known that I, \Vimann i\"[oiu.nv Man'rlx, a subject of the Kingof (treat Britain, residing at Fore street, ltedruth, in the county ofCormvall, England, analytical chemist, have invented a certain new anduseful Improved Process for the Sepa ration of Complex Ores, of whichthe 't'ollowing is a specification.

There are many complex ores in which the minerals are so combined orintimately associated tha' economical separation of the minerals hasbeen practically impossible, or where partial separation has beenellected with economy the separated material has still. consisted ofmixtures of a value considerably less than that indicated by analysis.Particular examples of such ores are those containing sultids of leadand zinc and other complex sulfids, and, as an instance of a somewhatdittercnt class of ore, the wolframtin ores, many tin and copper oresand arsenical ores generally. Two prime dit'tieulties present themselvesin the treatment of these ores. Tn the first place many of the ores arenot amenable to separation of their valuable constituents from thegangue by the simple washing processes which succeed with lesstroublesome ores, while in many cases even though this dilliculty is notexperienct-Pd, or is overcome by other processes of concentration. thereremains the ditliculty of separating the closely associated 'aluableconstituents in the concentrates, as for instance, the sull'ids of leadand zinc, which notwithstanding dit't'erences of specific gravity thatsullice in ordinary cases to furnish a basis for separation, can not besulliciently parted to a tltord products profitable for smelting. Theother prime ditliculty to which I refer is the loss experienced intreating most complex ores ot' the kind in question, owing to theparticles of crushed ore floating away with the water in any wet methodof concentration.

I have made a discovery with regard to such complex ores. It is thatmany of them 'an be more profitably treated by a water concentration, inthe sense that a better separation of their constituent minerals isattained and the amount of floating mineral is minimized, it thesubdivided ore or a concentrate of the ore is first mixed with asolution of an oxidizing agent of a kind which is adapted partially tooxidize the ore at a raised temperature, and then heating the mass.

()res have of course frequently been treated with oxidizing agents forvarious purposes, but whenever such treatment has been applied with aview to aiding separation of constituents of the ore by waterconcentration, the treatment has had for its object the oxidation of oneor more of the constituents so as to convert it or them into a solubleor insoluble oxidized product and thus to vary the relationship of thisconstituent or these constituents to the concentration process by theconversion into the oxidized product.

Now my treatment with an oxidizing agent may effect some oxidation, butinasmuch as the proportion of oxidizing agent which I use is very smallin comparison with the total amount of oxidizable material in the ore,the etlect produced in relation to the concentration process is not dueto the conversion of one or more constitucuts into oxidation products inthe sense oi the older tr'atment, and the valuable constituents of theore are recovered by the water eoru'entration in a substantiallyunaltered condition. Tn fact, it is clear to me that my treatment:succeeds under conditions which exclud 3 any save the very slightestoxidation; for in many instances the amount of: oxygen imparted to theore by the oxidizing agent. can be shown to be only a minute traction ofthat contained in the amount of oxidizing agent used. I have to admitthat at present l am unaware of the cause at the good ell'ect obtainedby my treatment.

According to my invention, I mix the suit ably subdivided ore. or insome cases a coin centrate thereoti with a solution of an oxidizingagent. The proportion of oxidizing agent to be used varies with thenature of the ore or concentrate under treatmen Generally speaking, thesmaller the proportion of gangue in an ore. the larger should be theproportion of oxidizing agent. It follows that a concentrate generallyreceives a more liberal addition than a crude ore. On the other hand,when one of the valuable eonstituents of the ore is in a very fine stateof division, the addition may be smaller than when all the constituentsare less finely divided. In any case, the proportion of oxidizing agentis small, seldom course, much more costly.

exceeding 2 per cent. of the weight of the ore. So far as I am atpresent aware, the proportion necessary for the best results cannot beascertained by analysis'of the ore or concentrate further than in therough manner indicated above. It is essential therefore to proceed bytrial on samples of the ore to ascertain the best proportion of centratemay be moistened with aqueous solutions of nitrate of soda of knownstrength, and heated in the manner described below. After the heatingoperation the samples are subjected to a water concentration; thatsample which gives the best result indicates the best proportion ofnitrate for the ore or concentrate in question. The proportion of waterused to dissolve the nitrate must be such that the powdered ore isthoroughly moistened by the solution. Excess of water is not injuriousbut is obviously unec0n0mi cal.

The moistened ore is introduced into any convenient furnace, the onlycondition to be observed being that when the ore is one theconcentration of which is rendered more difficult by an oxidizingroasting, air should be excluded; so too, when the ore is rich insilver, exclusion of air is desirable. In the furnace the ore shouldattain a temperature of a dull red heat; it need not be maintained atthis temperature for longer than a few minutes. After the heatingoperation the ore or concentrate is crushed, if neces sary, andsubjected to a water concentration, by which is meant gravitallyseparating by water, tendency of the particles to float being therebyavoided.

The selection of a nitrate for the process is determined by the questionof cost; at

present nitrate of soda is most economical;

equivalent of nitrate for the purpose of my invention. It is obviousthat moistening an ore containing a basic material with a solution ofnitric acid is equivalent to moisten.- ing the ore with a solution of anitrate.

I claim 1. A process of treating complex ores containing sulfids of leadand zinc or con centrates thereof so as to recover the valuableconstituents in a separated and substantially unaltered condition, whichprocess consists in mixing the subdivided material with a solution of anoxidizing agent of a kind adapted partially to oxidize the ore at araised temperature and in proportion insufficient to desulfurize theore, then heating the mass and finally gravita-lly separating by water.

2. A process of treating complex ores containing sulfids of lead andzinc or concentrates thereof so as to recover the valuable constituentsin a separated and substantially unaltered condition, which processconsists in mixing the subdivided material with a solution of a nitratein proportion insufficient to desulfurize the ore, then heating the massand finally gravitally separating by water.

3. A process of treating complex ores containing su'lfids of lead andzinc or concentrates thereof so as to recover the valuable constituentsin a separated and substantially unaltered condition, which processconsists in mixingthe subdivided material with a solution of nitrate ofsoda in proportion insufiicient to desulfurize the ore, then heating themass to a temperature not exceeding a dull red heat and finallygravital'ly separating by water.

In testimony whereof I have signed my name to this specification in thepresence of two subscribing witnesses. V V

IVILLIAM MORLEY MARTIN.

IVitnesses FREDERICK ANDREws, WILLIAM ARTHUR MiicLnAN.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. C.

